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Putting Double Check Valve Assembly before anti-siphon valve?

I currently have some Rainbird Jar-Top valves that have built in anti-siphon valves. They're working fine, but I know that over time they can loose their effectiveness so I was thinking about putting a double check valve assembly (from home depot or Lowe's) where I tapped the mainline for the irrigation system. Is there anything wrong with doing that? I mean will the DC interfere with the anti-siphon valves? Do the anti-siphon valves add any extra level of protection if they're down stream of a DC valve assembly or could I just put some plain valves down there and get rid of the eye sore those valves are since they stick up a foot above ground?

Thanks! I'm also about to setup a new system where the double check is required by city law. Would it be a good idea to put anti-siphon valves on each of my zones? Your comment makes me thing that DCs aren't all that great.

DCVAs are considered the low-end of backflow protection because of their potential to get fouled and fail.

Basically (as I understand it) "stuff" that can be in the water (even city water) can cause a check valve to get fouled and not seal properly. Of course you've got two of them, so even if one is fouled, the other one will still provide protection. But frequently, when something comes down the water pipe that can foul a check valve, there isn't just one... usually there are many. So there is the potential for both check valves to get fouled up at the same time.

Thanks for the info (I've used that link a lot, I like the information they provide). I'll have to talk to the City and see if they'll accept Anti-Siphon as an equivalent alternative and if not, I guess I'll put a filter upstream of the DC Valve.

Call your local water district and ask them what codes are to your area regarding proper back flow protection for sprinkler systems.

The DCVA is a great assembly, in my area- 95% of sprinkler systems, and 99% of fire sprinkler systems are DCVA's. Where I live an annual back flow test is required annually. ( My average annual tests are 1,400 back flow devices) . It is true, dcva are rated for low hazard.. However, In MANY area's, irrigation is considered Low Hazard. *This is depended on the department of health and their regulations in your region*

Yes, if you set up a fertigation system... A RPBA ( Reduced pressure back flow assembly) MUST be installed because this assembly is rated for High Hazard protection and has the best protection available.

( As far as the poster who said double checks get fauled up... this is true for any assembly lol)

I disagree with boots and highly recommend you get a backflow preventor into your system , what you choose is your choice and the codes in your area. ( Such as the double check, Reduced pressure back flow, Pressure Vacuum Breaker, Spill Resistant vacuum breaker. Anti-siphon valves are not to code on proper back flow protection. The main reason for this is because they are Non - Testable devices so you never know if it's truly working or not.

Thanks guys, I think that answers all of my question. I know that my City requires a DC valve assembly, but I'm hoping that they'll let me go with a RPBA in lieu of it since I want to use a fertilization system. As for my parents, I'll probably see if they're willing to add a DC valve upstream of the anti-siphon valves, but anti-siphon was all their city required and they work for their setup.

...........I disagree with boots and highly recommend you get a backflow preventor into your system , what you choose is your choice and the codes in your area. ( Such as the double check, Reduced pressure back flow, Pressure Vacuum Breaker, Spill Resistant vacuum breaker. Anti-siphon valves are not to code on proper back flow protection. The main reason for this is because they are Non - Testable devices so you never know if it's truly working or not.

He already has antisyphon valves, and if they are properly located, he has protection superior to what a DCVA can provide. If you can feed a mortuary table through a vacuum breaker, that speaks well of its ability to protect a water supply. But, since he has changed the story to now want fertilizer injection, nothing less than an RPZ will do. That goes in no matter what the city wants. If the city demands a DCVA, or else, then you give up on fertilizer injection, or go to the extreme of installing both a DCVA and an RPZ.